Photographic developing tank



Aug. 6, 1946. H, PECKHAM 2,405,233

PHOTOGRAPHIC DEVELOPING TANK Filed Jan. 9, i945 COLORED SHEATH IIII HIH FIG. I

ROBERT H. PECKHAM Patented Aug. 6, 1946 UNI TED STAT-ES PATENT OFF ICE BHOTOGRAPHIC DEVELOPING'IIANK Robert H. Peckham, United StatesNavy ApplicationJanuary 9, 1945, Serial No. 572, 042

" 2 Claims. (01. 95- -96) (Granted under the act of -March '3, 1 883, as

--amended April 30, 1928 370 0. G. L757) 'This. invention relatesto a device -for use in photography, and more 'especlally'to a'receptacle adapted to facilitate processing sensitized 'elements such as films,plates and records.

'Heretofore, it has been necessary 'to process sensitized elements such'as films, after exposure, that is, to develop and "fix the films in a dark room with the aid of artificial "light, usually "red light, the color, howevenbeing varied in accordance with the characteristic of the film "being processed. Dark "room operation is'at best difficult, and it is impossible in the light that is afforded to tell with'any certainty the progress of development or to study the photo-"recorded subject as it develops. Moreover, the elapse 'of time "between taking the undeveloped film or record into the dark room,'developingit and returning itin afinishedstate-for study, 'may be considerable, sincethe'dark room is usually 10- cated-ata place remote from the place atwhich the photograph is taken. This time 'element may be the difference between life'anddeath, particularly in "cases which require the study-of heart actions, and in'whichelectro-cardiographic records must'be processed by-development. --Similarly, time may be very important in otherphotographic work relating to medical examination. In this type of work,-it is highlydesirable -to-be able to study the results of the record orphotograph -at the bedside-of thepatient -so-that the attending physician may have the information before him immediately, and while he is observing the condition of the patient. With this in view, it igan-objectof this invention to'provide a device-for processing a sensitized element such as a film or record, immediately-upon removal from the camera, or :otherdevice for exposing the sensitized element,-'after exposure, which-will eliminate the necessityof a dark-room processing, which will permit continuous observation of the sensitized element throughout its development and which will be simple and effective for any typeof sensitized element, whetherit be of the type employed for making electro-cardiographic records, or the ordinary photosensitive film used in photographic work for technical'or esthetic purposes. 7

As-illustrated-herein, the invention resides in a device for-use in processingsensitized elements,- comprising a receptacle which consists ofa material which normallypermits the passage of all the components parts of visual radiant energy and a material which inhibits the passage of-aa material which inhibits the passage of that portion of radiant energy to'which the sensitized element being treated is most sensitive. More specifically, 'thedevice comprises a transparent receptacle into which the sensitized element may be placed'for processing, and a shield or sheath adapted-to envelope the receptacle, the shield'beingadapted "to transmit sufficient visual radiant energy to permit observation of the sensitized element 'duringthe processing, but having incorporatedtherein, "a material which will inhibit that portion of the visualradiant energy'to which the sensitized element is particularly sensitive from'getting to the sensitized element, so that further activation *of the sensitized element will nottake-place'during processing, even thoughthe receptacle is exposedto white light.

The inventiorrwill now be described with ref erenceto the accompanying drawingin which:

Fig. 1 is a-n'exploded view-ofa cylindrical receptacle for-receiving 'a sensitized element for development, together-with a shield incorporating-a material "for cutting out a givenportion of the visual 'radiantenergy;

-Fig.'-2 showsa perspective view of a rectangular receptacle and sheath; and

Fig. 3-shows aperspectiveview of a developing tray and-a shield'inthe'form of a cover-forthe tray.

This invention comprises a developing tank or tray Which-isto be usedfor developing sensitized elements such asphotographic film, paper; plates or records, but particularly recording paper 1 that has been-used in preparing electro-cardiographs, so that theattendant physician may examine the record during its development at the bedside of the patient, and hence-beable to determine almost immediately the nature of the heart action which has beenrecorded thereon. While the-invention is particularly useful in making the information recorded by photography immediately available, -it-is to beunderstood that it is'not confined -in-any aspect to medical Work, but it is equally applicable'to any kind of photographic work, and-when used, enables the person developing the-film or record to'study almost immediately the recorded information, whether this beof a-teohnical or esthetic -nature,without' the-necessity of adark room and dark room equipment.

The invention isbased upon the factthat sensitized-emu1sions have'been developed which are selectively sensitive to certain components of white light-and not to others. This sensitivity of -the emulsion can -be so carefully controlled that it-is possible-to develop'a filmhavinga sensitized emulsion of a given character in ordinary white light, provided a shield is provided which will prevent that part of the white light to which the emulsion is sensitive from reaching the film.

The idea of blocking out all of the light except that which is least active in changing the character of the emulsion in order to prevent further exposure, and the latter in only such a small amount that the film is but dimly visible, has been known for a long time, and has been practiced in some degree in the ordinary dark room where the film has been developed while exposed to a standard ruby light. However, it has not heretofore been thought possible to develop a photosensitive element except in the dark room, and in the dark room even when a ruby light is employed, it is practically impossible to determine with assurance the recorded information during the process of the development of the element.

The important aspect of the present invention resides in equipment for processing a sensitized element such as a photosensitive film or record in white light without further activation of the sensitized emulsion, and at the-same time, enabling an interested person to examine the recorded information as it develops. This can be accomplished by selecting a sensitized element that is sensitive to a given portion of white light but not to another portion thereof, and providing a shielding device which will not transmit any of the light to which the element is sensitive during the development thereof. For example, a shield may be made up which will transmit only about 50% of incident visual illumination by incorporating therein a uniform distribution of orange particles. For a film of a given sensitivity, this will act as sufficient protection for the sensitive emulsion during development and observe what is taking place. If an ortho-chromatic film is being developed, a shield incorporating red particles and transmitting about of visual illumination will provide protection against further activation and yet permit visual observation of the film. No attempt will be made herein to list the many kinds of sensitive emulsions, to what portion of white light they are sensitive and what should be used to shield them. It is sufiicient to say that for any sensitive emulsion there is a suitable material for blocking out substantially all of the radiant energy to which it is sensitive, or at least enough so that satisfactory results can be obtained.

As carried out herein, the invention takes the form of a developing tank or tray which consists of a material which transmits white light, and a material which inhibits the transmission of a given portion of white light, or is provided with a shield consisting of a material of like characteristic. The tank or its shield is selected so that it inhibits the passage of light which is detrimental to the sensitive emulsion of the film to be treated, that is, which will cause further activation thereof after the film has had its original exposure and yet permits the transmission of sufficient white light to enable the person developing the film to see what is taking place. In Fig. 1, there is shown a more or less exploded view of a cylindrical receptacle l0 which is composed of a clear glass or plastic, or other trans-, parent material having an opaque bottom 12 and an opaque rim M. A cover 16, composed of an opaque material, is provided which will fit tightly ture l5 centrally thereof through which may pass the handle of the film holder and agitator which is customarily disposed in receptacles of this character. The exposed film, together with the developing solution, is placed in the receptacle. This may be carried out in a dark room or any other convenient place from which light may be excluded. When this has been done, a shield l8 in the form of a cylindrical hollow sleeve is slipped over the body portion of the receptacle N], that is, the transparent portion thereof. The sleeve I8 extends from the bottom of the receptacle up to and engages the under edge of the rim l4, and is so selected that the collar will prevent transmission of that portion of the white light which would cause further activation of the film. When this is done, the receptacle may be taken outof the dark room into the light and the process of development may be continued in daylight without damage to the film, thereby enabling an interested person to observe the development of the film while it is taking place. Another form of receptacle is shown in Fig. 2, denoted by reference character 20. This receptacle is rectangular in cross section and consists of a body portion 22 which is composed of clear glass or plastic, an opaque bottom 24 and an opaque rim 26. An opaque cover 28 is provided which is adapted to fit over the rim 26, and a colored sheath 3|] is adapted to fit over the body portion of the receptacle up against the rim 26. In Fig. 3, there is shown still another form of developing receptacles, which in this case, takes the form of developing tray 32, the tray being formed of an opaque material and consisting of walls 34 and a bottom 36. A cover 38, composed of a colored material which will prevent the transmission of light rays which would further activate the film being developed, and yet will permit the transmission of suificient white light to enable the operator to observe what is going on, is provided.

It is to be observed that while each of the developing receptacles shown in Figs. 1, 2 and 3, are provided with sheaths which are formed of material including coloring matter which prevents the transmission of a given portion of white light, such sheaths are entirely unnecessary, since the transparent body of the receptacle itself may be formed of a material which incorporates particles of colored matter which will give the same efiect. The only advantage of a separate sheath is that a single receptacle may be provided with a plurality of sheaths to take care of different types of film, thus eliminating the necessity of an excessive number of receptacles.

While the invention has been described with reference to developing tanks, it is equally applicable to any other receptacle to be used for processing sensitized elements.

The invention described herein may be manu factured and used by and for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

l. A photographic film developing tank for strip type film wherein the film may be observed throughout its entire development comprising a base portion, a single cylindrical wall rising from the edges of the base portion, and a removable closure on the top of the chamber so formed, said removable closure being supported by the upper edge of the cylindrical wall, the wall portion beov the Tim the Cover ving the usual ape I8 tween the top and the base of the chamber being made of a material which will transmit substantially all light in the visible portion of the spectrum, and a separate light inhibiting filter of a generally cylindrical shape and having an inside diameter slightly greater than the outside diameter of the tank which filter when applied over the Wall of the chamber inhibits the passage therethrough of radiant energt in the portion of the spectrum to which the film being processed is most sensitive.

2. A photographic film developing tank wherein the process of development may be observed in ordinary room illumination as it takes place comprising, a container made of transparent material and formed to contain a developing solution therein, a substantially light-impervious cover for said container, and means for preventing the passage through the transparent portion of the container of light which will impair the film development including a filter means surrounding the container, said filter means inhibiting the passage Within the container of radiant energy in the range of the spectrum to which the film being processed is most sensitive, the container walls and filtering means being disposed around all the sides of the container to permit observation of the container contents from various angles and by reflection of light upon various portions of the container contents.

ROBERT H. PECKHAM. 

